In this work, resistive gas sensors based on dehydrohalogenated polyvinylidene difluoride irradiated by variable-energy (500–900 eV) Ar+ ions were investigated. The resulting ion-irradiated polyene-based films were investigated by scanning electron microscopy, energy dispersive x-ray spectroscopy, and Raman spectroscopy. The polyene-based structure was analyzed, and the variation in the films’ morphology, ordering, and graphitization degree with ion energy change was assessed. The resistive sensing response of the obtained composites to ammonia and ethanol was analyzed, revealing the energy- and analyte-dependent shift between positive and negative sensing responses. That allowed us to confirm that the sensing mechanism of the investigated structures is governed by electron or hole transfer induced by the interaction of vapor and the material, which results in various types of responses for the structures with n- and p-type conductivity.

The formation of polyene-polyyne-based nanocomposites by dehydrohalogenation of the drop-cast-deposited polyvinylidene fluoride, assessment and ion-induced tailoring of their gas sensing properties are reported. The investigated structure was analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy, revealing the thickness-dependent incomplete dehydrofluorination of the structure and its porosity induced by KOH treatment. The polyene-polyyne structures modified by low-energy Ar+ were studied by SEM and Raman spectroscopy, which showed the morphology variation, the shortening of chains and the graphitization of samples. The resistive gas sensing properties of the samples were analyzed at room temperature, revealing selective sensing of ammonia vapor by non-irradiated sample and the enhancement of the sensing properties for ethanol and water vapor after ion irradiation. With the ion dose enlargement, the change in the sensing response from electrical conductivity increase to decrease was observed for ammonia and ethanol, allowing us to discuss the origin and tunability of the sensing mechanism of the samples.

The films fabricated by heat treatment at 600–800°C of a material based on sp carbon synthesized by polyvinylidene fluoride dehydrofluorination are studied. The structure of the films is studied by scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. For the electron emission of the films, the turn-on field is 0.3–1.5 V/μm. The influence of the structure of the polyene and graphite phases having formed upon annealing on the emission characteristics of the material is considered. The emission is found to be caused by field emission and thermionic mechanisms.

Resistive sensing responses of the thin films obtained by dehydrohalogenation of polyvinylidene chloride (PVDC) and polyvinylidene chloride–polyvinyl chloride (PVDC-PVC) copolymer were investigated. The structure of the samples was studied by transmission electron microscopy, Fourier-transform infrared spectroscopy and Raman spectroscopy. The analyses demonstrate the formation of a porous structure based on polyyne–polyene chains. The formation of a foam-like oxidized sp-rich structure was observed for the samples obtained via the chemical treatment of the PVDC. However, a loose film with a developed structure and a lower fraction of sp-hybridized carbon was observed for KOH-treated PVDC-PVC. The resistive sensing responses of both of the dehydrohalogenated structures were measured for various concentrations of acetone, acetic acid, ammonia hydroxide, methanol, ethanol, benzene and water. The interplay between the efficiency of the dehydrohalogenation of the films, their structure and sensing selectivity is discussed.

The effect of changes in the energy and current of low-energy (100–600 eV) ion stimulation on the structure of carbon hydrogenated coatings with silver inclusions (a-CH:Ag) synthesized by pulsed-plasma deposition is investigated. Transmission electron microscopy, electron diffraction, electron-energy loss spectroscopy, X-ray photoelectron spectroscopy, and absorption in the UV and visible regions are used to study the influence of the stimulation energy and current on the manifestation of ion-induced effects, such as defect formation, selective silver sputtering, surface diffusion, and silver particle segregation.

In the work we studied films synthesized by RF-sputtering of monocrystalline polydiacetylene (PDA). Investigations of the structure were carried out by Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. We showed that obtained films had heterogeneous structure containing nanoscaled inclusions of initial PDA and irregularly distributed sp/sp2 fragments of carbon chains.

Carbon films were synthesized by pulse-plasma ion-assisted graphite sputtering in the atmosphere of argon-nitrogen mixture. The samples were studied by Raman spectroscopy, electron diffraction and XPS. According to the obtained data, nitrogen efficiently incorporates into the material structure, which leads to the formation of oriented graphite nanoclusters, which fraction reduces with ion assistance energy increase.

Carbon films fabricated by pulsed-plasma ion-assisted sputtering of graphite in argon and nitrogen atmosphere are studied using Raman spectroscopy, electron diffraction, and X-ray photoelectron spectroscopy. The results show that nitrogen is efficiently incorporated in the material structure, which leads to formation of oriented graphite nanoclusters the amount of which increases with an increase in the assistance energy.

Films obtained by radio-frequency sputtering of monocrystalline polydiacetylene (PDA) are under study. The structure is studied by Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It is shown that the obtained films have a heterogeneous structure containing agglomerates of nanosized inclusions of the initial PDA and irregular sp/sp2 hybridized carbon chain fragments.

This work presents the results of the X-ray photoelectron spectroscopy investigation of carbon films obtained by ion-plasma deposition at various plasma compositions. The detailed analysis of X-ray photoelectron spectra makes it possible to determine the structure of the deposited films and the influence of the presence of nitrogen and hydrogen in the plasma on the structure. Diamond-like films are obtained in pure argon plasma. The addition of nitrogen leads to a dramatic increase in the graphite-like phase while the addition of hydrogen corresponds to the formation of carbon chains.

X-ray photoelectron spectroscopy technique have been used to study carbon films obtained by means of ion-plasma deposition in the plasma of different chemical composition. The detailed analysis of electron spectroscopy data made it possible to determine the structure of the films and the influence of nitrogen and hydrogen admixture in plasma on the structural properties. Diamond-like films are obtained in pure argon plasma, graphite-like and carbon chain structures correspond to nitrogen and hydrogen addition respectively.

This paper presents the results of investigations of three types of carbon structures synthesized by different methods, such as arc discharge plasma enhanced chemical vapor deposition of carbon in a magnetic field, chemical dehydrohalogenation of the poly(vinyl chloride)/poly(vinylidene chloride) precursor, and pulsed plasma ion assisted deposition. It has been found that the samples prepared by different methods have a common feature, i.e., the presence of three-dimensional clusters based on sp 2 - or sp 3 -bonds surrounded by quasi-one-dimensional carbon chains. It has been shown that the structure of carbon materials changes depending on the synthesis conditions.

Nanocarbon material prepared via dehydrohalogenation of PVC-PVDC copolymer was studied in this work. The results of structural characterization of this material reveal the growth in the chain component fraction with increasing temperature of annealing that increases the specific capacity from 5 to 25 F/g. Chemical activation results in a noticeable growth of the specific capacity to 100 F/g.

Two-dimensional ordered linear-chain carbon films with different thicknesses (50 and 500 nm) have been studied by the tunneling spectroscopy method. The oscillatory dependence of the differential conductivity of the studied structures has been found. The obtained results have been interpreted with the use of the model of the formation of the charge density waves on the regular bends of the structure of linear-chain carbon.

Методом туннельной спектроскопии исследованы пленки двумерно-упорядоченного линейно-цепочечного углерода с разными толщинами (50 и 500 нм). Обнаружена осцилляционная зависимость дифференциальной проводимости исследуемых структур. Полученные результаты интерпретируются с использованием модели образования волн зарядовой плотности на регулярных изгибах структуры линейно-цепочечного углерода.